For the ultimate high performance street LS1/LS2/LS6 aluminum cylinder head AFR’s all new 205cc emission legal E/O # D250-4 are your only choice. Specifically designed for 1997 to present Gen-3 Chevy Corvettes, Camaros, and trucks. AFR’s LS1 cylinder head offers unmatched flow performance (298 CFM at .600lift) and features 2.020 intake and 1.600 exhaust valves with AFR’s iron ductile interlocking valve seats. With only 205cc port volume (same as stock LS1 head) this is an incredible 70 CFM increase over stock casting, creating unbelievable port velocity and performance.The 205cc cylinder head is ideal for normally aspirated 346C.I. to 396C.I. It is available with 66cc combustion chambers. AFR’s LS1 cylinder head is a direct bolt on, no special parts required. Structural features like Air Flow Research’s trademark 3/4” thick head deck, a must for blown and nitrous applications, reinforced rocker stud bosses, and thick wall runners provide unparalleled durability. An exclusive new modern combustion chamber design with double quench pad area helps the LS1 generate huge low and mid lift airflow numbers.